Prospects for clinical cancer metabolomics using stable isotope tracers

Abstract

Metabolomics provides a readout of the state of metabolism in cells or tissue and their responses to external perturbations. For this reason, the approach has great potential in clinical diagnostics. For more than two decades,, we have been using stable isotope tracer approaches to probe cellular metabolism in greater detail. The ability to enrich common compounds with rare isotopes such as carbon ( 13 C) and nitrogen ( 15 N) is the only practical means by which metabolic pathways can be traced, which entails following the fate of individual atoms from the source molecule to products via metabolic transformation. Changes in regulation of pathways are therefore captured by this approach, which leads to deeper understanding of the fundamental biochemistry of cells. Using lessons learned from pathways tracing in cells and organs, we have been applying this methodology to human cancer patients in a clinical setting. Here we review the methodologies and approaches to stable isotope tracing in cells, animal models and in humans subjects.

Stable Isotope-Resolved Metabolomics (SIRM) in Cancer Research with Clinical Application to NonSmall Cell Lung Cancer

“…The fraction of glucose consumed that was converted to lactate reached about 38 % (Fig. 2B) in the MDA-MB-231 cells, which is comparable to other cancer cell lines we have studied Lane et al, 2009aLane et al, , 2009b. Without labeling this information is impossible to obtain.…”

“…Stable isotopes offer several advantages, not only via their biocompatibility and nonhazardous nature, but also because stable isotopes such as 13 C or 15 N are readily distinguishable from their more abundant natural isotopes ( 12 C and 14 N) both by NMR and by mass spectrometry. These two techniques are sensitive, selective and can provide an enormous amount of information about the degree and which atoms are enriched from a particular precursor, even within a complex mixture Fan et al, 1986;Lane and Fan, 2007;Lane et al, 2008aLane et al, , 2009a. By using multidimensional techniques with isotope editing (NMR), or ultrahigh mass resolution, it is not necessary to separate the components from the rich mixture of compounds present in a cell extract or biofluid.…”

Regulation of mammalian nucleotide metabolism and biosynthesis

“…Such information cannot be obtained without tracer methods. These considerations point to the need to be able to assess the nucleotide synthesis according to tissue pathology and nature, for which these new technologies can now be applied with some ease (176,194,197–198,226–227). It is notable that many drugs are targeted at nucleotide synthesis at the level of the availability of nucleotides or act as chain terminators (32–39,228–229).…”

Stable isotope resolved metabolomics analysis of ribonucleotide and RNA metabolism in human lung cancer cells

“…In parallel, cells were also grown in 2 mM [U- 13 C, 15 N]-glutamine (Cambridge Isotope Laboratories, MA) plus 10 mM unlabeled glucose (Lane et al 2009). Cells were harvested by trypsinization at different times after exposure to the labeled glucose and washed 3 times in cold PBS to remove medium components as described previously (Fan et al 2005; Fan et al 2008).…”